1. Field of the Invention
This invention relates to seats in use for vehicles and, more particularly, to a seat frame used for vehicles.
2. Description of the Prior Art
An example of a conventional seat of this type is disclosed in FIGS. 1, 2, 3 and 4. Recliner lower arms 11, 11 are fixedly secured on the both sides of a seat frame 10 being in form of a box. Recliner upper arms 12, 12 are functionally connected with the recliner lower arms 11, 11. Functionally interposed between one recliner lower arm 11 and one recliner upper arm 12 is a seat recliner mechanism 13 which adjusts a back rest of a seat (not shown).
A seat sliding mechanism 14 comprises locking plates 16, 16 fixedly secured on brackets 15 fixed on a floor of a motor vehicle, a plurality of latch teeth 17 formed in the locking plates 16, lower rails 18 fixed on the locking plates 16, upper rails 20 movable in the forward and rearward direction by means of rollers 19 against the lower rails 18, a pawl 21 positioned inside of the recliner lower arms 11 and capable of engaging with one of the teeth 17, and an operational handle 22 functionally connected with the pawl 21 for releasing the engagement between one of the latch teeth 17 and the pawl 21.
In this conventional seat of a vehicle as shown in FIG. 3 and FIG. 4, when a load is placed on the seat back of the seat due to a collision of vehicles as shown by an arrow in FIG. 3, the load will be placed on the upper rail 20 in the upper direction as shown by an upper directional arrow in FIG. 4 and on the lower rail 18 in the lower direction as shown by an lower directional arrow in FIG. 4. Since there are no means which place restrictions on the spread of flange portions 20a and 20b of the upper rail 20 and the spread of flange portions 18a and 18b of the lower rail 18, the flange portions 20a, 20b, 18a, 18b will spread and enlarge and the seat sliding mechanism 14 will thus be destroyed.
Furthermore, the construction of a conventional seat frame shows that a bracket is interposed between a seat frame and a back rest frame for combining both frames and that the combination of the bracket and the seat frame is formed by bringing the same into surface contact with each other and by using a pin or a bolt to connect them together. Therefore, a large load is centered at the pin or the bolt on collision of the vehicles. As a result, the pin or the bolt is damaged, or the seat frame and the bracket is damaged. In order to prevent this damage it is necessary to enlarge the thickness of the conventional bracket and the seat frame and the diameter of the pin or bolt. This means, however, increasing the weight of the seat which thus makes it heavy and difficult to handle. That is to say, this contradicts the possibility of saving energy where the weight of the vehicle is to be lightened.